> I definitely do the "manager doubling" when it comes to estimates. If I think it'll take a month, I estimate 2 months to my boss. If I have to report several levels up, I multiply by 2 for every level.

Hah, I like this. Every level up that sees it is also a potential for more scope creep, as each person will have their own vision of what's being produced.

One of my favorite estimating guidelines from a mentor was that development tasks are either 2, 4, or 8 hours. If it's more than 8 hours it can be broken up into smaller tasks.